AMBLYOPIA

Amblyopia or Lazy eye is a condition with underdeveloped vision in one or both the eyes during infancy. Amblyopia is a frequent condition, occurring in about three or four of every 100 children. When a child is born with normal eyes, he or she has the potential for good vision in both eyes, but must learn to see with each of them. If for some reason, the child prefers to use one eye more than the other, the preferred eye learns to see well but the other suffers from lack of use. It does not learn to see as well, even with glasses. The non-preferred eye is said to be lazy or have amblyopia.  This vulnerable period of visual development ends around age eight or nine. Children under the age of 8 are at much higher risk of developing Amblyopia, as the vision development almost stops at this age. There are chances of improvement in vision after the age of 8, but the extent to which it could improve depends on the prognosis at an early age. If not detected early and treated in time, Amblyopia can even result in permanent vision loss.

One common cause for lazy eye is strabismus. When the child’s eyes are pointed in different directions, the child has to use one eye at a time to avoid seeing double. If he or she uses one eye more than the other, the other eye becomes lazy.

 Children without strabismus can also develop a lazy eye. Even though their eyes are straight, one eye is preferred more than the other. The non-preferred eye becomes lazy and does not learn to see.

Detection of Amblyopia

Amblyopia does not bother the child because there are no symptoms. It is found only by checking the vision in each eye. This can be done fairly accurately in any child three years or older. For this reason, all children should have their vision tested by age four.

Usually, Amblyopia cannot be detected by just looking at the child’s eyes. It requires a few simple tests which will be performed by an optometrist and an ophthalmologist.

Tests

A complete eye examination is warranted which includes vision testing in both the eyes by asking the child to read the letter on a visual acuity chart followed by the refractive power testing to rule out if there is any refractive error such as hypermetropia, myopia and astigmatism which will be tested with and without using eye drops. The eye alignment will be assessed to see if there are any squint which could be a reason for amblyopia which will be followed by general structural examination using a microscope and ophthalmoscope.
These include:

Visual Acuity – The patient reads letters from an eye chart to evaluate the vision. Very young children may be tested by looking at pictures instead of letters.

Motility Exam – A doctor examines the eyes to see if they are properly aligned and if there is any muscle dysfunction.

Refraction – As part of the exam, the doctor places a series of corrective lenses in front of the eyes to find the correct lens power the patient needs to compensate for a refractive error (near-sightedness, farsightedness or astigmatism).

Treatment of Amblyopia

The treatment for amblyopia involves forcing the lazy eye to be used more often. Usually this is accomplished by temporarily blurring the preferred, or good, eye. This can be accomplished with patching or drops.  This treatment may have to be continued for several months until each eye sees equally well. Fortunately, when caught at an early age, it is usually successful in restoring good sight. Sometimes the patching must be continued intermittently until age nine. If the lazy eye is out of focus, eyeglasses may be required, in addition to patching the good eye to obtain the best sight.

The amblyopia could be treated with the use of glasses or contact lenses, eye patching, eye exercises, eye drops and, in some cases, surgical treatment may be required.

Glasses or Contact Lenses: Glasses play a major role in treating amblyopia as this is the only way to correct the refractive error. In some cases where one eye has the higher refractive error than the other eye, use of contact lenses can be of great value than glasses.

Eye Patching: Eye patches are used to occlude the eye with better vision to stimulate the lazy eye to see more. The eye with better vision is patched with the help of a biocompatible eye patch when the child is wearing glasses. In some children both the eyes are required to be patched alternatively. Duration of patching of eyes varies depending on the severity of the condition.

Children who are not co-operative with the patching of eyes can be administered with the eye drops in the eye with better vision to blur its vision temporarily. This way the lazy eye is stimulated or forced to see more.

Eye Exercises: There are some computer-based eye exercises wherein the child is required to play video games and solve puzzles in a supervised manner wearing 3D glasses.

Surgery: Children with amblyopia due to squinting of the eye require surgical intervention.

Duration of the treatment depends on the levels of improvement of vision in the patient which usually continues until equal vision is maintained in both the eyes.